The present invention relates to an image input apparatus for picking up images of objects such as various kinds of documents, a person, and the like. A conventional image input apparatus of this type will be explained below with reference to FIGS. 24 and 25. Referring to FIG. 24, reference numeral 301 denotes a lens; 302, a camera head which incorporates a CCD element and its circuit board (neither are shown); and 303, an arm which is constituted by a bellows- or spiral-shaped metal pipe. A signal cable is inserted through the arm 303, which can be bent to an arbitrary shape. Reference numeral 304 denotes a base which incorporates a main circuit board (to be described later) and is coupled to a chassis which also serves as a weight; 305, a monitor connected via a cable 306; 307, an original; 308, an operator or his or her position; and 309, an image of the operator as an object displayed on the monitor 305.
A portrait photographing operation as a typical use method of the conventional image input apparatus with the above-mentioned arrangement will be described below. First, the operator turns on a power switch (not shown) arranged on the base 304. Then, an image of the object (person) picked up by the camera head 302 is displayed on the monitor 305. In the case of FIG. 24, since the camera head 302 picks up an image of the photographer at the position 308, the monitor 305 displays the image 309 of the operator. At this time, a focusing ring provided to the lens 301 is turned to attain a focusing operation, as needed.
A document photographing operation for picking up an image of the original 307 placed on the desk will be described below. When the document photographing operation is performed, the operator holds the camera head 302 to move it to a position 302a indicated by a broken line in FIG. 24. Since the arm 303 is constituted by the bellows-shaped metal pipe that can be bent to an arbitrary shape, the operator can easily move the camera head 302.
The operator places the original 307 with respect to the camera head 302 moved to the position 302a, so that the lower side of the original is located on the base side (erected state when viewed from the base 304), as shown in FIG. 24. The original 307 must be placed in such direction since the CCD is attached to the camera head 302 to have a normal up-and-down direction in the portrait photographing operation. For this reason, in the document photographing operation, the up-and-down direction of the original 307 must be set in correspondence with the direction of the CCD, as shown in FIG. 24. With this adjustment, an image of the original 307 picked up by the camera head 302 at the position 302a can be displayed on the monitor 305 to have a normal direction, thus realizing a document photographing operation. At this time, the focusing ring provided to the lens 301 is turned to attain a focusing operation, as needed.
The internal arrangement of the base 304 will be described below with reference to FIG. 25. Referring to FIG. 25, the base 304 comprises a cylindrical portion 304a for holding the arm 303, and is fixed to a chassis 315 by screws (not shown). A main circuit board 316 is fixed to the chassis 315 by screws. Circuit boards 317, 318, and 319 are connected to the main circuit board 316 via connectors 320, 321, and 322, thus assuring a board area by effectively utilizing the internal space of the base 304.
The main circuit board 316 also has a connector 316a for receiving a cable (in this embodiment, a flexible circuit board consisting of polyimide) for transferring signals from the camera head 302, and an image output terminal for receiving the cable 306 (FIG. 24). The chassis 315 comprises a substantially cubic block 315a consisting of a zinc-based material. The block 315a has not only a role of the bottom plate to which the main circuit board 316 and the base 304 are attached, but also a role of a weight that stably supports the entire apparatus.
However, the above-mentioned prior art suffers the following problems.
(1) When the position of the original 307 is offset from the front side of the main body 304 in the document photographing mode, the camera head 302 must be moved to the center of the original 307, and its inclination must then be adjusted in correspondence with the direction of the original 307. However, as described above, since the arm 303 that supports the camera head 302 is constituted by the bellows-shaped pipe, it can only be bent only slowly. Therefore, the position of the original 307 that can be followed by the camera head 302 is limited.
(2) Since the arm 303 is flexible, it is difficult for the operator due to a so-called spring back to move and adjust the position of the camera head to that the operator intended. Furthermore, the operator must check the image of the original 307 displayed on the screen of the monitor 305 while performing the above-mentioned operation, resulting in poor operability.
In the above-mentioned prior art, the focus ring of the lens 301 has no indices indicating in-focus distances. For this reason, the operator cannot initially determine the direction to turn the ring, resulting in poor operability. The operator may become accustomed with this operation to some extent as he or she uses this apparatus for a long time. However, if the operator operates the focus ring a certain interval after his or her previous operation, the same problem as described above may be posed upon restarting the operation.
In the above-mentioned prior art, as shown in FIG. 25, since the base 304 which covers the main circuit board 316 consists of a resin material, the entire main circuit board 316 cannot be electrically shielded. Note that the chassis 315 can shield the circuit board 316 not entirely but partially. In an image input apparatus of this type, noise against an image signal has a considerable influence on the image quality of an output image. The conventional apparatus is weak against noise since the main circuit board 316 which mounts a large number of electronic elements and the like cannot be sufficiently shielded. The image quality of an output image may often deteriorate under the influence of noise.
In the above-mentioned prior art, especially in the document photographing mode, there is no reference or index that indicates the position of the original 307 to be placed. In addition, the camera head 302 is free to move, and is difficult to be fixed in position. The operator must change the position of the original 307 or move the camera head 302 in a trial-and-error manner while gazing the displayed image of the original 307, so as to normally display the image of the original 307 on the screen of the monitor 305, resulting in cumbersome operations. As described above, when the original 307 is to be placed, troublesome positioning operations are required in association with the camera head 302, resulting in poor operability.